The lack of evidence for PET or PET/CT surveillance of patients with treated lymphoma, colorectal cancer, and head and neck cancer: a systematic review

Localized Rectal Cancer: Indian Consensus and Guidelines

The rising incidence of colorectal cancer (CRC) in India, particularly the prevalence of rectal cancer over colon cancer (0.7:1), has been a growing concern in recent decades; especially notable is the trend of increasing cases among young CRC patients. Given the diverse treatment approaches for rectal cancer globally and the varying economic capacities of patients in low to middle-income countries (LMICs) like India, it is essential to establish consensus guidelines that are specifically tailored to meet the needs of these patients. To achieve this, a panel comprising 30 eminent rectal cancer experts convened to conduct a comprehensive and impartial evaluation of existing practices and recent advancements in the field. Through meticulous scrutiny of published literature and a consensus-building process that involved voting on pertinent questions, the panel formulated management strategies. These recommendations are the result of a rigorous, evidence-based process and encapsulate the collective wisdom and judgment of leading authorities in the field.

Diagnostic Performance of F-18 FDG PET/CT in the Detection of Recurrent Colorectal Cancer: Correlation with Biochemical Markers and Conventional Imaging Modalities

Background/Objectives: Although the role of PET/CT imaging is well established in oncology, its diagnostic value in routine monitoring for recurrent colorectal cancer (CRC) is still controversial. The aim was to evaluate the diagnostic value of F-18 FDG PET/CT in detecting recurrent CRC in correlation with CEA, CA 19-9 levels, and conventional imaging modalities (CIM). Methods: Between 2009 and 2023, a retrospective study was performed including 134 CRC patients referred for PET/CT imaging on the suspicion of recurrence, based on elevated CEA and/or CA 19-9 and/or equivocal CIM findings. According to our institution's Tumor Board CRC protocol, after the initial treatment, which was dependent on the TNM stage (neoadjuvant therapy, primary resection, or adjuvant treatment), patients underwent a standard 5-year surveillance including CEA and CA 19-9 measurements, CIM, and colonoscopy, every six months. The statistics, including univariate and multivariate analyses were conducted using the IBM SPSS 20.0 statistical software. p-values < 0.05 were considered statistically significant. Results: Recurrent CRC was confirmed in 54/134 (40.3%) patients with elevated tumor markers. PET/CT showed high diagnostic performance in detecting recurrent CRC with sensitivity, specificity, PPV, NPV, and accuracy of 94.4%, 82.5%, 78.5%, 95.7%, and 87.3%, respectively. The CEA showed a high sensitivity of 98.1% but both low specificity and accuracy of 15% and 48.5%, respectively. The sensitivity, specificity, and accuracy for CA 19-9 and CIM for diagnosis of CRC recurrence were 44.4%, 67.5%, 58.2%, and 51.9%, 98.8%, 79.9%, respectively. The AUC for PET/CT, elevated CEA levels, CIM, and elevated CA 19-9 levels was 0.885 (95% CI: 0.824-0.946; p < 0.001), 0.844 (95% CI: 0.772-0.916; p < 0.001), 0.753 (95% CI: 0.612-0.844; p < 0.001), and 0.547 (95% CI: 0.442-0.652; p = 0.358), respectively. Univariate analysis showed that both PET/CT and CIM positive results were highly associated with CRC recurrence (p < 0.001 and p < 0.001, respectively). At the same time, gender, mucinous tumor type, presence of initial lymph node metastasis (N+), and presence of initial distant metastasis (M+) had no significance (p = 0.211, p = 0.158, p = 0.583, and p = 0.201, respectively). Our multivariate analysis showed that independent predictors for CRC recurrence are positive PET/CT scans (p < 0.001), positive CIM results (p = 0.001), and elevated CA 19-9 levels (p = 0.023). Although CA 19-9 was not detected as a statistically significant predictor in the univariate analysis (p = 0.358), in a multivariate analysis it was recognized as a significant predicting factor in detecting the CRC recurrence (p = 0.023). Conclusions: F-18 FDG PET/CT showed high diagnostic efficacy in CRC recurrence detection, in correlation with CEA levels, CA 19-9 levels, and CIM. This imaging modality should be routinely integrated into the post-operative follow-op in patients with elevated tumor markers.

Survivorship in Early-Stage Rectal Cancer Patients Who Have Received Combined Modality Therapy

Survival rates in early-stage rectal cancer patients have increased over the past few decades. Societies such as the National Comprehensive Cancer Network (NCCN), American Cancer Society (ACS), American Society of Clinical Oncology (ASCO), and European Society of Medical Oncology (ESMO) have proposed guidelines related to cancer survivorship care including formal recommendations to address the needs in early-stage rectal cancer survivors. These guidelines, in addition to new clinical research findings in survivorship will be reviewed, specifically looking at physical, psychosocial, and financial concerns in rectal cancer survivorship.

Optimized 18F-FDG PET-CT Method to Improve Accuracy of Diagnosis of Metastatic Cancer

The diagnosis of cancer by FDG PET-CT is often inaccurate owing to subjectivity of interpretation. We compared the accuracy of a novel normalized (standardized) method of interpretation with conventional non-normalized SUV. Patients (n = 393) with various malignancies were studied with FDG PET/CT to determine the presence or absence of cancer. Target lesions were assessed by two methods: (1) conventional SUV_max (conSUV_max) and (2) a novel method that combined multiple factors to optimize SUV (optSUVmax), including the patient's normal liver SUV_max, a liver constant (k) derived from a review of the literature, and use of site-specific thresholds for malignancy. The two methods were compared to pathology findings in 154 patients being evaluated for mediastinal and/or hilar lymph node (MHLNs) metastases, 143 evaluated for extra-thoracic lymph node (ETLNs) metastases, and 96 evaluated for liver metastases. OptSUV_max was superior to conSUV_max for all patient groups. For MHLNs, sensitivity was 83.8% vs. 80.7% and specificity 88.7% vs. 9.6%, respectively; for ETLNs, sensitivity was 92.1% vs. 77.8% and specificity 80.1% vs. 27.6%, respectively; and for lesions in the liver parenchyma, sensitivity was 96.1% vs. 82.3% and specificity 88.8% vs. 23.0%, respectively. Optimized SUV_max increased diagnostic accuracy of FDG PET-CT for cancer when compared with conventional SUV_max interpretation.

Application of circulating tumour cells to predict response to treatment in head and neck cancer

Background

Local recurrence and metastasis remain the major causes of death in head and neck cancer (HNC) patients. Circulating tumour cells (CTCs) are shed from primary and metastatic sites into the circulation system and have been reported to play critical roles in the metastasis and recurrence of HNC. Here, we explored the use of CTCs to predict the response to treatment and disease progression in HNC patients.

Methods

Blood samples were collected at diagnosis from HNC patients (n = 119). CTCs were isolated using a spiral microfluidic device and were identified using immunofluorescence staining. Correlation of baseline CTC numbers to 13-week PET-CT data and multidisciplinary team consensus data were conducted.

Results

CTCs were detected in 60/119 (50.4%) of treatment naïve HNC patients at diagnosis. Baseline CTC numbers were higher in stage III vs. stage I-II p16-positive oropharyngeal cancers (OPCs) and other HNCs (p = 0.0143 and 0.032, respectively). In addition, we found that baseline CTC numbers may serve as independent predictors of treatment response, even after adjusting for other conventional prognostic factors. CTCs were detected in 10 out of 11 patients exhibiting incomplete treatment responses.

Conclusions

We found that baseline CTC numbers are correlated with treatment response in patients with HNC. The expression level of cell-surface vimentin (CSV) on CTCs was significantly higher in patients with persistent or progressive disease, thus providing additional prognostic information for stratifying the risk at diagnosis in HNC patients. The ability to detect CTCs at diagnosis allows more accurate risk stratification, which in the future may be translated into better patient selection for treatment intensification and/or de-intensification strategies.

Supplementary information

The online version contains supplementary material available at 10.1007/s13402-022-00681-w.

Colorectal cancer (CRC) monitoring by 6-monthly 18FDG-PET/CT: an open-label multicentre randomised trial

Background

[¹⁸F]2-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (¹⁸FDG-PET/CT) has high sensitivity for detecting recurrences of colorectal cancer (CRC). Our objective was to determine whether adding routine 6-monthly ¹⁸FDG-PET/CT to our usual monitoring strategy improved patient outcomes and to assess the effect on costs.

Patients and methods

In this open-label multicentre trial, patients in remission of CRC (stage II perforated, stage III, or stage IV) after curative surgery were randomly assigned (1 : 1) to usual monitoring alone (3-monthly physical and tumour marker assays, 6-monthly liver ultrasound and chest radiograph, and 6-monthly whole-body computed tomography) or with 6-monthly ¹⁸FDG-PET/CT, for 3 years. A multidisciplinary committee reviewed each patient’s data every 3 months and classified the recurrence status as yes/no/doubtful. Recurrences were treated with curative surgery alone if feasible and with chemotherapy otherwise. The primary end point was treatment failure defined as unresectable recurrence or death. Relative risks were estimated, and survival was analysed using the Kaplan–Meier method, log-rank test, and Cox models. Direct costs were compared.

Results

Of the 239 enrolled patients, 120 were in the intervention arm and 119 in the control arm. The failure rate was 29.2% (31 unresectable recurrences and 4 deaths) in the intervention group and 23.7% (27 unresectable recurrences and 1 death) in the control group (relative risk = 1.23; 95% confidence interval, 0.80–1.88; P = 0.34). The multivariate analysis also showed no significant difference (hazards ratio, 1.33; 95% confidence interval, 0.8–2.19; P = 0.27). Median time to diagnosis of unresectable recurrence (months) was significantly shorter in the intervention group [7 (3–20) versus 14.3 (7.3–27), P = 0.016]. Mean cost/patient was higher in the intervention group (18 192 ± 27 679 € versus 11 131 ± 13  €, P < 0.033).

Conclusion

¹⁸FDG-PET/CT, when added every 6 months, increased costs without decreasing treatment failure rates in patients in remission of CRC. The control group had very close follow-up, and any additional improvement (if present) would be small and hard to detect.

ClinicalTrials.gov identifier

NCT00624260

The Utility of PET/Computed Tomography for Radiation Oncology Planning, Surveillance, and Prognosis Prediction of Gastrointestinal Tumors

At present, the strongest evidence for the use of PET/computed tomography (CT) in gastrointestinal (GI) malignancies is to rule out distant metastatic disease at diagnosis, radiation treatment planning for anal malignancies, and disease recurrence monitoring in colorectal and anal malignancies. Use of PET/CT for GI malignancies continues to evolve over time, with new studies evaluating prognostic abilities of PET/CT and with increasing sensitivity and spatial resolution of more modern PET/CT scanners. The authors encourage future applications and prospective evaluation of the use of PET/CT in the staging, prognostication, and recurrence prediction for GI malignancies.

Consensus and controversies regarding follow-up after treatment with curative intent of nonmetastatic colorectal cancer: a synopsis of guidelines used in countries represented in the European Society of Coloproctology

AIM

It is common clinical practice to follow patients for a period of years after treatment with curative intent of nonmetastatic colorectal cancer, but follow-up strategies vary widely. The aim of this systematic review was to provide an overview of recommendations on this topic in guidelines from member countries of the European Society of Coloproctology, with supporting evidence.

METHOD

A systematic search of Medline, Embase and the guideline databases Trip database, BMJ Best Practice and Guidelines International Network was performed. Quality assessment included use of the AGREE-II tool. All topics with recommendations from included guidelines were identified and categorized. For each subtopic, a conclusion was made followed by the degree of consensus and the highest level of evidence.

RESULTS

Twenty-one guidelines were included. The majority recommended that structured follow-up should be offered, except for patients in whom treatment of recurrence would be inappropriate. It was generally agreed that clinical visits, measurement of carcinoembryoinc antigen and liver imaging should be part of follow-up, based on a high level of evidence, although the frequency is controversial. There was also consensus on imaging of the chest and pelvis in rectal cancer, as well as endoscopy, based on lower levels of evidence and with a level of intensity that was contradictory.

CONCLUSION

In available guidelines, multimodal follow-up after treatment with curative intent of colorectal cancer is widely recommended, but the exact content and intensity are highly controversial. International agreement on the optimal follow-up schedule is unlikely to be achieved on current evidence, and further research should refocus on individualized 'patient-driven' follow-up and new biomarkers.

Atypical Metastasis of p16-Positive Tonsillar Squamous Cell Carcinoma to the Pleura: A Case Report

Incidence rates and patterns of distant metastases of head and neck malignancies are well documented in the literature, such that focused management strategies are routinely practiced in anticipation of their likely behavior. Head and neck tumors are known to most commonly metastasize to the lungs, skeletal system, and liver, generally within 2 years of definitive treatment and in the context of poor locoregional control of the primary lesion. Recent studies, however, have shown that human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma (SCCa) tumors display different patterns of distant metastases than those traditionally described for head and neck HPV-negative SCCa tumors. This finding has substantial implications for how patients undergoing treatment of these cancers should be surveilled after therapy. This report describes a case of p16-positive tonsillar SCCa with metastasis to a highly unusual secondary site in the pleura to show an example of the unconventional patterns of distant metastases reported for HPV-positive oropharyngeal SCCa in the recent literature. We aim to provide a more thorough understanding of this case by discussing the pathogenesis of metastatic spread to the pleura and the clinical progression generally observed in patients with secondary pleural malignancy. This report goes on to investigate how behaviors of distant metastases exhibited by HPV-positive oropharyngeal SCCa differ from those of more conventionally described head and neck HPV-negative SCCa and the implications thereof for strategies of post-treatment surveillance of these tumors going forward.

False Positive Positron Emission Tomography / Computed Tomography Scans in Treated Head and Neck Cancers

OBJECTIVE

Positron emission tomography/computed tomography (PET/CT) imaging for head and neck cancers (HNC) is commonly utilized for post-treatment assessment. Though PET/CT in this setting has been reported to have high negative predictive values (> 90%), positive predictive values have been reported at approximately 50%, leading to high rates of false positivity (FP) and troubling management decisions for both patient and practitioner. The objective of this study was to identify patient, disease, treatment and imaging factors that might be associated with a higher likelihood of FP on initial post-treatment PET/CT imaging for patients treated for HNC.

MATERIALS AND METHODS

A retrospective chart review was performed on 84 patients treated for HNC who received radiation therapy (RT) as part of their overall management from October 2005 to August 2013. Of the patients screened, 19 were found to have mucosally based squamous cell carcinoma (SCC) with positive initial post-treatment PET/CT studies (23%). Fisher's exact test was used to analyze the association between categorical variables and FP, including patient's gender, disease laterality, primary tumor site and stage, nodal and overall stage, high dose RT fraction size, number of RT fractions completed, total RT dose, biologically effective dose and timing of PET/CT acquisition. Wilcoxon rank-sum test was used to analyze the association between continuous variables and FP, including patient age, total elapsed days of RT, an amount of infused fluorodeoxyglucose 18F-FDG, pre-PET/CT serum glucose levels, and maximum standardized uptake value SUVmax. Statistically significant findings were those that were deemed p <0.05.

RESULTS

Among patients with positive initial post-treatment PET/CT scans for treated HNC, there was a lower proportion of higher primary disease stage associated with FP versus true positivity (T-stage 3-4: 20 vs 78%, respectively, p=0.023). We also discovered that 50% of patients that underwent confirmation for FP findings suffered serious complications as a direct consequence of invasive exploratory procedures.

CONCLUSIONS

Although PET/CT is known for its exceptional negative predictive value (> 90%) in the post-treatment setting for HNC, high rates of FP remains a clinical challenge. Our study suggests that tumor stage (T-stage) may impact FP rates in positive initial post-treatment PET/CT scans. We recommend careful multidisciplinary discussion regarding positive PET/CT studies in the post-treatment setting for HNC, particularly if invasive intervention is considered.

FDG-PET imaging in hematological malignancies

The majority of aggressive lymphomas is characterized by an up regulated glycolytic activity, which enables the visualization by F-18 FDG-PET/CT. One-stop hybrid FDG-PET/CT combines the functional and morphologic information, outperforming both, CT and FDG-PET as separate imaging modalities. This has resulted in several recommendations using FDG-PET/CT for staging, restaging, monitoring during therapy, and assessment of treatment response as well as identification of malignant transformation. FDG-PET/CT may obviate the need for a bone marrow biopsy in patients with Hodgkin's lymphoma and diffuse large B cell lymphoma. FDG-PET/CT response assessment is recommended for FDG-avid lymphomas, whereas CT-based response evaluation remains important in lymphomas with low or variable FDG avidity. The treatment induced change in metabolic activity allows for assessment of response after completion of therapy as well as prediction of outcome early during therapy. The five-point scale Deauville Criteria allows the assessment of treatment response based on visual FDG-PET analysis. Although the use of FDG-PET/CT for prediction of therapeutic response is promising it should only be conducted in the context of clinical trials. Surveillance FDG-PET/CT after complete remission is discouraged due to the relative high number of false-positive findings, which in turn may result in further unnecessary investigations. Future directions include the use of new PET tracers such as F-18 fluorothymidine (FLT), a surrogate biomarker of cellular proliferation and Ga-68 CXCR4, a chemokine receptor imaging biomarker as well as innovative digital PET/CT and PET/MRI techniques.

Trends in the Use of (18)F-Fluorodeoxyglucose PET Imaging in Surveillance of Non-Small-Cell Lung and Colorectal Cancer

PURPOSE

Surveillance PET after curative-intent treatment of non-small-cell lung cancer (NSCLC) or colorectal cancer (CRC) is not clearly supported by available evidence or the Choosing Wisely campaign. However, the frequency of PET imaging during the surveillance period is relatively unknown.

METHODS

Using Surveillance, Epidemiology, and End Results-Medicare data, 65,748 patients aged 66 years or older who were diagnosed with stage I to IIIA NSCLC or stage I to III CRC from 2001 through 2009 and who underwent surgical resection were identified. Trends in "any PET" or "PET-only" use 6 to 18 months postoperatively were assessed.

RESULTS

Any PET use more than doubled over the study period. Eleven percent of patients with NSCLC and 4% of those with CRC diagnosed in 2001 received any PET, compared with 25% of patients with NSCLC and 13% of those with CRC in 2009 (P < .001 for both). Higher stage disease was correlated with higher PET utilization and faster growth in use over the study period. PET-only use also increased over the study period, especially in higher stage disease. Fewer than 2% of patients diagnosed with stage IIIA NSCLC in 2001 received PET only, compared with 15% of patients diagnosed in 2009 (P = .014). Similarly, 1% of patients diagnosed with stage III CRC in 2001 received PET only, compared with 8% of patients diagnosed in 2009 (P < .001).

CONCLUSIONS

PET utilization during the surveillance period increased between 2001 and 2009. Further research is needed to determine the factors driving use of surveillance PET and to examine relationships between PET and patient outcomes.

Use of Positron Emission Tomography to Detect Recurrence and Associations With Survival in Patients With Lung and Esophageal Cancers

BACKGROUND

Positron emission tomography (PET) scans are often used in cancer patients for staging, restaging, and monitoring for treatment response. These scans are also often used to detect recurrence in asymptomatic patients, despite a lack of evidence demonstrating improved survival. We sought to evaluate utilization of PET for this purpose and relationships with survival for patients with lung and esophageal cancers.

METHODS

Using national Surveillance, Epidemiology, and End Results (SEER) and Medicare-linked data, we identified incident patient cases from 2005 to 2009, with follow-up through 2011. We identified cohorts with primary lung (n = 97 152) and esophageal (n = 4446) cancers. Patient and tumor characteristics were used to calculate risk-adjusted two-year overall survival. Using Medicare claims, we examined PET utilization in person-years (to account for variable time in cohorts), excluding scans for staging and for follow-up of CT findings. We then stratified hospitals by quintiles of PET utilization for adjusted two-year survival analysis. All statistical tests were two-sided.

RESULTS

There was statistically significant variation in utilization of PET. Lowest vs highest utilizing hospitals performed .05 (SD = 0.04) vs 0.70 (SD = 0.44) scans per person-year for lung cancer and 0.12 (SD = 0.06) vs 0.97 (SD = 0.29) scans per person-year for esophageal cancer. Despite this, for those undergoing PET, lowest vs highest utilizing hospitals had an adjusted two-year survival of 29.0% (SD = 12.1%) vs 28.8% (SD = 7.2%) for lung cancer (P = .66) and 28.4% (SD = 7.2%) vs 30.3% (SD = 5.9%) for esophageal cancer (P = .55).

CONCLUSIONS

Despite statistically significant variation in use of PET to detect tumor recurrence, there was no association with improved two-year survival. These findings suggest possible overuse of PET for recurrence detection, which current Medicare policy would not appear to substantially affect.

Role of fluorine 18 fluorodeoxyglucose positron emission tomography/computed tomography in gastrointestinal cancers

Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) has become a routine imaging modality for many malignancies and its use is currently increasing. In the present review article, we will summarize the evidence for FDG-PET/CT use in digestive cancers (excluding neuroendocrine tumours), and review the existing recommendations. While PET/CT is nowadays considered to be an important tool in the initial workup of oesophageal and anal cancers, new data are emerging regarding its use in assessing therapeutic efficacy, radiotherapy treatment planning, and detection of recurrence in case of isolated tumour marker elevation. Moreover, PET/CT may help decision making by detecting distant metastatic sites especially in potentially resectable metastatic colorectal cancer and, to a lesser extent, in localized gastric and pancreatic cancers. Finally, incidental focal colonic FDG uptakes require exploration by colonoscopy, as they are often associated with premalignant or malignant lesions.

Surveillance radiologic imaging after treatment of oropharyngeal cancer: a review

The increasing proportion of human papilloma virus-related oropharynx cancers has led to improved success in the treatment of this disease. However, the current low recurrence rate after treatment of oropharyngeal cancer highlights the continued need for, as well as the challenges of, designing an effective follow-up surveillance program. There are frequently multiple modalities used in the treatment of oropharyngeal cancer, resulting in short- and long-term tissue changes to the head and neck that challenge clinical distinction of recurrence versus treatment-related changes. The oropharynx subsite is characterized by complex anatomy not always accessible to physical exam, making radiologic imaging a potentially useful supplement for effective follow-up assessment. In this manuscript, the literature regarding the type of radiologic imaging modality and the frequency of obtaining imaging studies in the surveillance follow-up after treatment of oropharyngeal cancer is reviewed. While ultrasound and MRI have useful characteristics that deserve further study, PET/CT appears to have the best sensitivity and specificity for imaging surveillance follow-up of head and neck cancers including oropharyngeal cancer. A negative PET/CT is particularly useful as a predictor of prognosis and can guide the clinician as to when to stop obtaining additional imaging studies in the absence of clinical signs of recurrence. However, there is scant evidence that imaging surveillance can improve survival outcomes. Suggestions to guide future imaging surveillance research studies are provided.

Positron Emission Tomography (PET) in Oncology

Since its introduction in the early nineties as a promising functional imaging technique in the management of neoplastic disorders, FDG-PET, and subsequently FDG-PET/CT, has become a cornerstone in several oncologic procedures such as tumor staging and restaging, treatment efficacy assessment during or after treatment end and radiotherapy planning. Moreover, the continuous technological progress of image generation and the introduction of sophisticated software to use PET scan as a biomarker paved the way to calculate new prognostic markers such as the metabolic tumor volume (MTV) and the total amount of tumor glycolysis (TLG). FDG-PET/CT proved more sensitive than contrast-enhanced CT scan in staging of several type of lymphoma or in detecting widespread tumor dissemination in several solid cancers, such as breast, lung, colon, ovary and head and neck carcinoma. As a consequence the stage of patients was upgraded, with a change of treatment in 10%-15% of them. One of the most evident advantages of FDG-PET was its ability to detect, very early during treatment, significant changes in glucose metabolism or even complete shutoff of the neoplastic cell metabolism as a surrogate of tumor chemosensitivity assessment. This could enable clinicians to detect much earlier the effectiveness of a given antineoplastic treatment, as compared to the traditional radiological detection of tumor shrinkage, which usually takes time and occurs much later.

Metabolic activity of primary uveal melanoma on PET/CT scan and its relationship with monosomy 3 and other prognostic factors

Purpose

To correlate the metabolic activity of primary uveal melanoma on positron emission tomography (PET)/CT scan with known clinical and pathological prognostic factors.

Methods

A retrospective cohort analysis of eyes enucleated for uveal melanoma that underwent preoperative imaging with a PET/CT scan was performed. Tumour dimensions were recorded and classified using Collaborative Ocular Melanoma Study (COMS) and American Joint Committee on Cancer (AJCC) Tumour - Nodes - Metastases (TNM) criteria. Metabolic activity was determined by measurement of the maximal standardised uptake value (SUVmax) on PET/CT scans. SUVmax of >2.5 and >4 was also used as cut-off value for metabolic positivity. Chromosome 3 and 8 status was determined using fluorescence in situ hybridisation analysis. Pearson correlation, χ² test and non-parametric tests were used. p<0.05 was considered statistically significant.

Results

Seventy-six uveal melanomas were imaged preoperatively with a PET/CT scan. Overall 92% of tumours had a SUVmax >2.5 and 67% had a SUVmax >4. Monosomy 3 was found in 35 melanomas, of which 94% had an SUVmax >2.5 and 80% had an SUVmax >4. Only 57% of disomy 3 melanomas had an SUVmax >4. SUVmax was significantly increased in tumours with monosomy 3 (p=0.043) but not in tumours with chromosome 8 gain (p=0.49). SUVmax and increasing tumour size were positively correlated (p<0.05). Using the AJCC criteria, there was a significant difference in SUVmax among prognostic groups (p=0.024). There was no correlation with histopathological cell type (p=0.923).

Conclusions

Metabolic activity of uveal melanoma on PET/CT scan is positively correlated with monosomy 3, increasing tumour size and TNM prognostic groups. No association with chromosome 8 gain or histopathology cell type was noted. SUVmax >4 is a relative but not an absolute indicator of monosomy 3 status.

Molecular imaging in stem cell therapy for spinal cord injury

Spinal cord injury (SCI) is a serious disease of the center nervous system (CNS). It is a devastating injury with sudden loss of motor, sensory, and autonomic function distal to the level of trauma and produces great personal and societal costs. Currently, there are no remarkable effective therapies for the treatment of SCI. Compared to traditional treatment methods, stem cell transplantation therapy holds potential for repair and functional plasticity after SCI. However, the mechanism of stem cell therapy for SCI remains largely unknown and obscure partly due to the lack of efficient stem cell trafficking methods. Molecular imaging technology including positron emission tomography (PET), magnetic resonance imaging (MRI), optical imaging (i.e., bioluminescence imaging (BLI)) gives the hope to complete the knowledge concerning basic stem cell biology survival, migration, differentiation, and integration in real time when transplanted into damaged spinal cord. In this paper, we mainly review the molecular imaging technology in stem cell therapy for SCI.